Abstract:The effects of pH，temperature，oxygen，metal ions，vitamin C（VC）and hot-air drying temperature on the color change of Porphyra yezoensis were investigated using colorimetry.Brightness of P.yezoensis increased significantly（p<0.05）with increase in solution alkalinity and the strong alkalinity resulted in a lighter color when the solution pH≥9.The redness of P.yezoensis in pH 10-14 solutions changed significantly（p<0.05）.And the strong alkalinity of the solution produced a weaker red color and more intense green color of samples.The pH change of solutions from strong to weak and weak to strong acidity led to more intense blue and yellow P.yezoensis，respectively.The total color difference of the sample in pH 5-9 solutions did not change significantly（p>0.05）.At temperatures of 0-40℃，the color change of P.yezoensis was not significant（p>0.05）.However，further increase in temperature to≥70 ℃ changed the sample color to brighter green and yellow.During heating at 40℃，the low oxygen environment produced by the vacuum rendered P.yezoensis less bright and bluer.Porphyra yezoensis treated using VCsolution became redder in color.Calcium and magnesium ions and hot-air drying temperature did not have obvious effects on the color ofP.yezoensis.